Suspension System for Transfemoral Prosthesis

1. Suspension Systems of
Transfemoral Prosthesis
BY-
ROHAN GUPTA
MPO 1ST YEAR, 3RD BATCH, PDUNIPPD
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2. What are Suspension Systems ?
The System by which the prosthesis is held to the limb is referred as Suspension.
When the prosthesis is suspended perfectly and there is no relative motion
between the socket and the limb.
Motion occurs because of a faulty or inadequate suspension system.
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3. Importance of Suspension Systems !
• This is a crucial factor in the design of a prosthesis.
• The suspension is how the socket kept on the residual limb preventing it to fall
off when the leg is lifted up or moved during gait.
• Good suspension will improve the energy transfer, enhance the control of the
prosthesis, and decrease any discomfort or abrasions.
• When suspension is poor the leg will feel heavy and may lead to skin
breakdown.
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4. Factor for Prescription of Suspension depends on ?
• For suspension prescription the patient will need to be thoroughly assessed not
just with regard to the residuum shape and length, but also their overall
strength, hand dexterity, eye sight and balance in standing.
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5. 1. Cuffs, Straps and Belts
• Also called Auxillary suspension.
• This is the original way of keeping the socket on and prevent it from falling off
during the swing phase. Even though this and “old” way of suspension it is still
used today as it is an inexpensive, simple, reliable and durable way of
suspension.
• This can vary from a simple soft strap/cuff to a very rigid band around the
pelvis.
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6. Advantages of Cuffs, Straps and Belts
• Belts or straps can be used as a primary suspension method if other methods fail
or are not appropriate.
• It can also be used as a secondary option for when negative pressure or suction
is used.
• It is also indicated for an individual with a short residuum, who have changing
volume of their residuum, this keeps the socket on even if the socket fit is loser at
the end of the day or poor hip abductor strength.
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7. Dis-advantages of Cuffs, Straps and Belts
• It is warm.
• Pressure around the pelvis area.
• Needs good hand dexterity and strength.
• Moves when sitting.
• Uncomfortable.
• Provides minimal suspension.
• Can cause bruising or chafing.
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9. 2. Lanyard
• This is when a cord or strapped is attached to lower end of the liner.
• As the individual inserts the residuum with the liner on the cord/strap will go
through a small hole in the bottom of the socket.
• The cord is then pulled tight, to draw the residuum into the socket. The lanyard
is then attached with a mechanism on the outside of the prosthesis to keep it
secure.
• Used for transfemoral suspension.
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10. Advantages of Lanyard
• Easy to don (put on) the prosthesis in a seated position, especially for someone
with poor eyesight or balance.
• It provides a secure suspension and decreases socket rotation.
• Inexpensive.
• Simple.
• Reliable.
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11. Dis-advantage of Lanyard
• Needs some hand dexterity and strength.
• A liner is needed for suspension.
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13. 3. Self Suspending Socket
• This is when the suspension is created by the socket brim (top part) on the
residuum.
• The brim part is made to extend and narrow over the joint (example over the
knee joint) in order to create a grasp or hold over the joint.
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15. 4. External Sleeve
• A sleeve that fits snugly over the socket and then extends onto the individual’s
thigh is used to seal in the air in the socket and in that way create a suspension.
• Sleeves are made from different materials including neoprene, silicone or
copolymer gel.
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16. Advantages of External Sleeve
• Pistoning (movement of the residuum inside the socket) is reduced with an
airtight seal.
• Sleeves are flexible and usually allows the knee to bend (if the sleeve has a
ribbed or wave design over the knee joint) and it is cosmetic as it covers the top
edge of the socket.
• It is a reliable form of suspension and relatively inexpensive.
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17. Dis-advantages of External Sleeve
• Sleeves without a ribbed or wave design can cause abrasion over the patella.
• If applied incorrectly the person can get a skin irritation where the sleeve
touches the skin.
• Needs hand dexterity and strength.
• The sleeve’s effectiveness is reduced with wear and tear, a hole in the sleeve can
lead to a loss of suction.
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19. 5. Pin and Lock
• A silicon or gel liner with a pin at the bottom of the liner is used on the residual
limb.
• When the limb is placed into the socket the pin has to go into a locking
mechanism at the bottom of the socket.
• This mechanism will lock the pin in place, creating a secure suspension in the
socket.
• A release mechanism can be pressed to unlock the pin.
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20. Advantages of Pin and Lock
• Provide a positive mechanical lock with auditory feedback for the user when the
pin engages.
• Relatively easy donning and doffing and can be done in a sitting position.
• More forgiving with volume fluctuations.
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21. Dis-advantages of Pin and Lock
• Due to the pulling down action of the pin on the liner an elongation effect can
happen at the bottom of the residuum and cause skin breakdown, but newer
liners are reinforced with a matrix to avoid this from happening.
• Wear and tear on liners.
• When the pin is misaligned or the liner is donned incorrectly the locking
mechanism will not be engaged, this might be difficult for someone not having
the ability to bend down or with poor eyesight.
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23. 6. Suction without a liner
• The socket is made with an expulsion valve that will let the air out to create a
seal once the residuum is in and the valve is closed.
• The suction is created between the bare skin and the inside of the socket.
• To achieve this, the individual will have to pull the residuum into the socket
using a piece of material, a special sock, cord or webbing.
• By opening or pushing on the suction valve the air will return, breaking the seal
and thereby releasing the residuum to remove the prosthesis.
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24. Advantages of Suction without a liner
• With an accurate fit the suspension will be very good.
• Less expensive than options with liners
•
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25. Dis-advantages of Suction without a liner
• When the socket is donned poorly the suction will not hold and there will be
poor suspension.
• It is an old way of suspension.
• Donning can be complex for some individuals as it requires hand strength and
dexterity as well as balance in standing.
• Not secure suspension with volume fluctuations or if there is a failure with the
valve.
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27. 7. Suction with a liner
• A liner that is donned on the residuum is used to create suction instead of the
skin suction described above.
• These liners are usually made of silicone or gel, to create a seal with the inside of
the socket the liner can have silicone rings/ribs or a membrane.
• The air can escape through the valve as the socket is donned and will keep the
suction once the valve is closed.
• Some sockets have a one-way valve.
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28. • By opening or pushing on the suction valve the air will return, breaking the seal
and thereby releasing the residuum to remove the prosthesis.
• Lubricant or an alcohol solution on the seal will help the liner to slide in and to
create a seal.
• When using suction with a liner an external sleeve is not necessary, unless there
are severe volume fluctuations.
• he liner is usually covered with material to help it last longer.
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29. Advantages of Suction with a liner
• Even pressure throughout the socket.
• Secure fit.
• Donning in a seated position is possible.
• Used to stabilize excess residual tissue.
• Good suspension even with small volume fluctuations.
• Liner and socket donning does not have to be as precise to secure suspension
but may cause rotation in the socket.
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30. Dis-advantages of Suction with a liner
• Relatively expensive.
• Wear and tear on liners.
• Poor suspension with significant volume fluctuations.
• Good hand strength and dexterity needed.
• Lubricant is needed for donning.
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32. 8. Vacuum-Assisted Suspension
• Also known as Negative Pressure, Elevated Vacuum or Dynamic Vacuum.
• Suction suspension is created with direct contact between the liner (or with the
membranes on the liner) and the socket wall.
• With this system a mechanism/pump sucks the air out between the liner and the
socket creating a negative pressure that is the same across the entire surface.
• To seal off the system an external sleeve or seal is used at the top of the socket.
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33. Advantages of Vacuum-Assisted Suspension
• The mechanism creates a constant negative pressure and allows for better
suspension when there is volume fluctuation.
• Less pistoning and rotation occur within the socket.
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34. Dis-advantages of Vacuum-Assisted Suspension
• More expensive.
• Mechanical components that can break.
• Adds weight to the prosthesis.
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36. 9. Elevated Vaccum - Advantages
• Very firm suspension providing excellent security and improved proprioception.
• Elevated vacuum tends to assist in maintaining more constant limb volume,
thereby decreasing the need to add additional socks.
• Elevated vacuum assists with wound healing by improving circulation through
the residual limb.
• Provides good distal comfort for bony and sensitive distal ends; as long as the
socket fits properly with good volume and length matching.
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38. 10. Osseo integration
• This procedure can be done on patients with a short above knee amputation.
• An implant is placed within the remaining femur bone.
• When it is healed and the bone attached to the implant an osseointegrated
prosthesis can be directly attached to the implant in the bone.
• No need for a socket or liner.
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39. Advantages of Osseo integration
• Physiological weight-bearing, better mobility because the socket is not
restricting.
• Easy donning and doffing.
• Osseoperceptive sensory feedback that allows for more precise control over the
prosthesis.
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40. Dis-advantages of Osseo integration
• Cost of surgery and specific components for the prosthesis.
• Risk of infection and other complications such as delayed wound healing or
bodily fluid leakage from the implant.
• Extensive rehabilitation is needed.
• With some implants, no weight bearing is allowed for 6 months.
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42. THANK YOU
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